mam.mwism
... About nomenclature Numbers with “M” in front of them are Messier objects, cataloged by Charles Messier between 1758 to 1782. These were about 100 diffuse structures often mistaken for comets. ...
... About nomenclature Numbers with “M” in front of them are Messier objects, cataloged by Charles Messier between 1758 to 1782. These were about 100 diffuse structures often mistaken for comets. ...
August 2015 BRAS Newsletter
... telescope, a soft, bluish-green glow can be seen to surround the ‘dumbbell’; and was the first planetary nebula discovered – by Charles Messier in 1764. Brocchi’s Cluster, Al Sufi’s Cluster, Collinder 399, The Coathanger (asterism), mag. 3.6, 19 25.4 +20 11, 90’, is a group of stars with magnitudes ...
... telescope, a soft, bluish-green glow can be seen to surround the ‘dumbbell’; and was the first planetary nebula discovered – by Charles Messier in 1764. Brocchi’s Cluster, Al Sufi’s Cluster, Collinder 399, The Coathanger (asterism), mag. 3.6, 19 25.4 +20 11, 90’, is a group of stars with magnitudes ...
First Light: Physical Characterization of Early Star Formation in the
... picture, dwarf galaxies may represent protogalactic fragments that have not yet been accreted into larger galaxies. However, a recent VLT spectroscopic study of red giants in four dwarf spheroidal companions to the Milky Way found very different chemical signatures in even the oldest dwarf spheroida ...
... picture, dwarf galaxies may represent protogalactic fragments that have not yet been accreted into larger galaxies. However, a recent VLT spectroscopic study of red giants in four dwarf spheroidal companions to the Milky Way found very different chemical signatures in even the oldest dwarf spheroida ...
Observations and three-dimensional photoionization modelling of
... empirical analysis. However, we notice obvious discrepancies between helium temperatures derived from the model and the empirical analysis, as overestimated by our model. This could be due to the presence of a small fraction of cold metal-rich structures, which were not included in our model. It is ...
... empirical analysis. However, we notice obvious discrepancies between helium temperatures derived from the model and the empirical analysis, as overestimated by our model. This could be due to the presence of a small fraction of cold metal-rich structures, which were not included in our model. It is ...
Parameters of massive stars in the Milky Way and nearby galaxies
... atmospheres that include sphericity, mass-loss and line-blanketing, in addition to NLTE. The combination of all these factors results in temperatures that are much cooler than those hitherto assumed. Vacca et al. (1996) presented a compilation of the spectroscopic determinations of effective temper ...
... atmospheres that include sphericity, mass-loss and line-blanketing, in addition to NLTE. The combination of all these factors results in temperatures that are much cooler than those hitherto assumed. Vacca et al. (1996) presented a compilation of the spectroscopic determinations of effective temper ...
l000 first detection of polarized scattered light from an
... model, thus indicating that the error distribution is close to Gaussian and the binned data reveal the true variations. To evaluate the robustness of the solution to the measurement errors as well as to properly evaluate the errors of the model parameters, we employed the Monte Carlo method. Followi ...
... model, thus indicating that the error distribution is close to Gaussian and the binned data reveal the true variations. To evaluate the robustness of the solution to the measurement errors as well as to properly evaluate the errors of the model parameters, we employed the Monte Carlo method. Followi ...
First detection of polarized scattered light from an exoplanetary
... 2006) for detecting directly starlight that is scattered in a planetary atmosphere and, thus, possesses information on its geometry, chemistry, and thermodynamics. However, due to the anticipated very low polarization degree of ∼10−5, a practical use of this method was generally attributed to the fu ...
... 2006) for detecting directly starlight that is scattered in a planetary atmosphere and, thus, possesses information on its geometry, chemistry, and thermodynamics. However, due to the anticipated very low polarization degree of ∼10−5, a practical use of this method was generally attributed to the fu ...
Diapositive 1
... radial overtone. Right: Fourier Sp after pre-whiten (f1, 2f1) multiperiodic (mono before). Models: 10.2 M, 18 Myr evolved beta Cep star (Aerts et al. 2006). N.B.: MOST’s first target! ...
... radial overtone. Right: Fourier Sp after pre-whiten (f1, 2f1) multiperiodic (mono before). Models: 10.2 M, 18 Myr evolved beta Cep star (Aerts et al. 2006). N.B.: MOST’s first target! ...
–1– Solutions to PH6820 Midterm 1. Define the following: molecular
... sizes range from 10 M⊙ (for a dark globule) to 106 M⊙ for the most massive giant molecular clouds. Typical kinetic temperatures range from 10-50 K. The average densities are around 50-100 cm−3 . They often show filamentary and clumpy morphologies. A molecular core is a self gravitating globule withi ...
... sizes range from 10 M⊙ (for a dark globule) to 106 M⊙ for the most massive giant molecular clouds. Typical kinetic temperatures range from 10-50 K. The average densities are around 50-100 cm−3 . They often show filamentary and clumpy morphologies. A molecular core is a self gravitating globule withi ...
Document
... •Sun emits with the spectrum of a black body at temperature of 5800 oK, superimposed with the absorption lines specific of elements. From the line intensitites one decudes the abundances of elements, with respect to hydrogen.. •Helium has been discovered in the solar corona, but due to the position ...
... •Sun emits with the spectrum of a black body at temperature of 5800 oK, superimposed with the absorption lines specific of elements. From the line intensitites one decudes the abundances of elements, with respect to hydrogen.. •Helium has been discovered in the solar corona, but due to the position ...
Nonuniform viscosity in the solar nebula and large masses of Jupiter
... than the intermediate region. The more efficient viscosity drives faster radial inflow of material during the nebula evolution. Because the inflow in the outer region is faster than the intermediate region, the material tends to accumulate in Jupiter-Saturn region which is between the outer and inte ...
... than the intermediate region. The more efficient viscosity drives faster radial inflow of material during the nebula evolution. Because the inflow in the outer region is faster than the intermediate region, the material tends to accumulate in Jupiter-Saturn region which is between the outer and inte ...
superbubbles vs super-galactic winds
... several thousands of O stars strongly correlated in space (within a radius much smaller than 100 pc). All massive stars undergo strong stellar winds and all of them with a mass larger than 8 M will end their evolution exploding as supernova. And therefore, one is to expect from our hypothetical clu ...
... several thousands of O stars strongly correlated in space (within a radius much smaller than 100 pc). All massive stars undergo strong stellar winds and all of them with a mass larger than 8 M will end their evolution exploding as supernova. And therefore, one is to expect from our hypothetical clu ...
DISCOVERY OF HOT SUPERGIANT STARS NEAR THE GALACTIC
... been classified by Bohannan & Crowther (1999) as WN9ha-type stars, a unique subgroup of WR star exhibiting significant hydrogen content from the Pickering-Balmer decrement (h suffix), with the upper Balmer lines showing intrinsic absorption components (a suffix). On the other hand, HD 153919 is clas ...
... been classified by Bohannan & Crowther (1999) as WN9ha-type stars, a unique subgroup of WR star exhibiting significant hydrogen content from the Pickering-Balmer decrement (h suffix), with the upper Balmer lines showing intrinsic absorption components (a suffix). On the other hand, HD 153919 is clas ...
SPICA Science for Transiting Planetary Systems
... photometric accuracy of ~10-4 in a few minutes cadence • Variations due to difference of a few ten K in large surface area of planets would be detectable – Variations caused by a few hundred K difference in day/night side of hot Jupiters have already been detected with Spitzer’s ~1x10-3 accuracy ...
... photometric accuracy of ~10-4 in a few minutes cadence • Variations due to difference of a few ten K in large surface area of planets would be detectable – Variations caused by a few hundred K difference in day/night side of hot Jupiters have already been detected with Spitzer’s ~1x10-3 accuracy ...
Chapter 10 Late evolution of low- and intermediate
... flash’ that has the power to disrupt the whole star. However, observations of white dwarfs in rather young open clusters tell us that this probably never happens in real AGB stars, even when the total ...
... flash’ that has the power to disrupt the whole star. However, observations of white dwarfs in rather young open clusters tell us that this probably never happens in real AGB stars, even when the total ...
Antlia, the Machine Pneumatique
... it has an uneven surface brightness with a faint, barely seen nucleus. A short arcNearly two degrees south-west of alpha shape of a few faint stars curls out from Antliae, Jay O’Neal picked up an asterism the galaxy’s western side (see sketch). in this galaxy-strewn area. “Exciting” is This nearly e ...
... it has an uneven surface brightness with a faint, barely seen nucleus. A short arcNearly two degrees south-west of alpha shape of a few faint stars curls out from Antliae, Jay O’Neal picked up an asterism the galaxy’s western side (see sketch). in this galaxy-strewn area. “Exciting” is This nearly e ...
Axions and White Dwarfs
... where a and b are constants of the order of unity that depend on the details of the model, and R and T are the stellar radius and the temperature at the region of period formation, respectively. This equation reflects the fact that, as the star cools down, the degeneracy of the plasma increases, the ...
... where a and b are constants of the order of unity that depend on the details of the model, and R and T are the stellar radius and the temperature at the region of period formation, respectively. This equation reflects the fact that, as the star cools down, the degeneracy of the plasma increases, the ...
www.astro.caltech.edu
... While the majority of detected GRBs originate from massive stars, a smaller subset sees to have a completely different physical cause (Figure 2). The host galaxies of short-duration GRBs (those whose gamma-ray emission lasts for 2 seconds or less) observed with Keck have been localized to a complete ...
... While the majority of detected GRBs originate from massive stars, a smaller subset sees to have a completely different physical cause (Figure 2). The host galaxies of short-duration GRBs (those whose gamma-ray emission lasts for 2 seconds or less) observed with Keck have been localized to a complete ...
An Earth mass planet orbiting Alpha Centauri B
... Exoplanets down to the size of Earth have been found, but not in the habitable zone, i.e. the distance to the parent star where water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for obvious reasons, such as tidal locking, strong stellar act ...
... Exoplanets down to the size of Earth have been found, but not in the habitable zone, i.e. the distance to the parent star where water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for obvious reasons, such as tidal locking, strong stellar act ...
1. Basic Properties of Stars
... Why do some stars have strong lines of hydrogen, others strong lines of calcium? The answer was not composition (all stars are 95% hydrogen) but rather surface temperature. As temperature increases, electrons are kicked up to higher levels (remember the Bohr model) by collisions with other atoms. La ...
... Why do some stars have strong lines of hydrogen, others strong lines of calcium? The answer was not composition (all stars are 95% hydrogen) but rather surface temperature. As temperature increases, electrons are kicked up to higher levels (remember the Bohr model) by collisions with other atoms. La ...
How do we know what stars are
... as the star ages. When helium begins to fuse together, elements like ____________ and ___________ appear in the spectrum. Heavier and heavier elements will be formed as the core runs out of hydrogen and helium. Stars cannot fuse atoms larger than the element __________. Toward the end of the life of ...
... as the star ages. When helium begins to fuse together, elements like ____________ and ___________ appear in the spectrum. Heavier and heavier elements will be formed as the core runs out of hydrogen and helium. Stars cannot fuse atoms larger than the element __________. Toward the end of the life of ...
Document
... wide variety of systems, from an ideal gas to a cluster of galaxies to a star in equilibrium! ...
... wide variety of systems, from an ideal gas to a cluster of galaxies to a star in equilibrium! ...
talk
... CO detectable far out in the Milky Way, M33, NGC 4414, and probably all spirals with extended HI. Molecular fraction seems to decrease more sharply than pressure in outer disk. Metallicity apparently not a problem for CO detection, despite claims to the contrary except at low Z and high ISRF. Heati ...
... CO detectable far out in the Milky Way, M33, NGC 4414, and probably all spirals with extended HI. Molecular fraction seems to decrease more sharply than pressure in outer disk. Metallicity apparently not a problem for CO detection, despite claims to the contrary except at low Z and high ISRF. Heati ...
Steps
... Our and others’ simulations show that S/N>15 needed to do detailed stellar population analysis (stellar ages, metallicities, sigma, dust with 10% accuracy or better) ...
... Our and others’ simulations show that S/N>15 needed to do detailed stellar population analysis (stellar ages, metallicities, sigma, dust with 10% accuracy or better) ...
Read the article
... flares seen in X-rays and Infrared wavelengths, occurring close to the galactic center, have further emboldened this view. We have reanalyzed the motions of these stars, and studied the data in X-rays and Infrared wavelengths using different image processing techniques. Here we report the existence ...
... flares seen in X-rays and Infrared wavelengths, occurring close to the galactic center, have further emboldened this view. We have reanalyzed the motions of these stars, and studied the data in X-rays and Infrared wavelengths using different image processing techniques. Here we report the existence ...
Planetary nebula
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word ""nebula"" is Latin for mist or cloud and the term ""planetary nebula"" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.A mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energises the shell of nebulous gas around the central star, appearing as a bright coloured planetary nebula at several discrete visible wavelengths.Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances.In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About one-fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may play a role.